Such a device comprises a box containing an electronic central unit and an internal power supply module connected to the central unit. The central unit is arranged to process signals, data, and other information, to perform calculations, to control the display of images or the delivery of sounds, . . . . The internal power supply module generally comprises a direct-current/direct-current (DC/DC) converter that delivers current presenting characteristics appropriate for powering the central unit and the other components of the device. The internal power supply module is connected by an electric cable to an external power supply block provided with a member for connection to the power supply network that delivers AC power having data signals superposed thereon, and with a converter for converting the AC power into DC power. It is known to have one external data transmission module per carrier current. The external data transmission module is an interface that separates or combines data signals and a carrier current in order to enable the central unit to exchange data with the network. The external transmission module is provided with means for connecting it to the power supply network and it is connected to the central unit by an Ethernet type connection cable. This requires two electricity outlets to be available in the vicinity of the location of the device: one for connecting the power supply block and the other for connecting the external transmission module.
In order to obviate that drawback, it is known to incorporate the transmission module in the external power supply block such that the power supply block is connected to the central unit via a combination cable comprising both a two-wire power cable and an Ethernet connection cable. The AC power for the device is then the carrier current. The combination cable fitted with its special connectors is relatively expensive. In addition, the power supply block is found to be relatively bulky.